I found online ICO image converter today. It is easy and take a few seconds to convert any image into ico format. It is support PNG, JPEG, GIF, BMP with 2 mb maximum file size.
It is convert in 16×16, 32×32, 48×48, 128×128 dimensions and also you can convert all the sizes of same image at time. It support 16.7M & 256 color depth.
Go and check out : http://www.icoconverter.com/